Display device and method of manufacturing same

ABSTRACT

A display device including a substrate, a plurality of pixel electrodes arranged in a form of a matrix in a plane parallel with the substrate, a display functional layer exerting an image display function on a basis of an image signal supplied to the plurality of pixel electrodes, a driving electrode opposed to the plurality of pixel electrodes, and a plurality of detecting electrodes arranged in a form of a plane opposed to the driving electrode, separated and arranged at a pitch of a natural number multiple of an arrangement pitch of the pixel electrodes in one direction in the arrangement plane, and each capacitively coupled with the driving electrode.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.15/698,232 filed Sep. 7, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/575,092 filed Dec. 18, 2014, now U.S. Pat. No.9,791,951 issued Oct. 17, 2017, which is a continuation of U.S. patentapplication Ser. No. 12/706,808 filed Feb. 17, 2010, now U.S. Pat. No.9,459,718 issued Oct. 4, 2016, the entireties of which are incorporatedherein by reference to the extent permitted by law. The presentapplication claims the benefit of priority to Japanese PatentApplication No. JP 2009-040728 filed on Feb. 24, 2009 in the JapanPatent Office, the entirety of which is incorporated by reference hereinto the extent permitted by law.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a display device having a function of acapacitance type touch sensor (contact detecting device) enablinginformation input by contact of a finger of a user or the like, and amethod of manufacturing the display device.

2. Description of the Related Art

The contact detecting device is generally a device detecting that afinger of a user, a pen or the like comes into contact with or proximityto a detecting surface.

A contact detecting device referred to as a so-called touch panel isknown. The touch panel is formed so as to be superimposed on a displaypanel, and enables information input as a substitute for ordinarybuttons by making various buttons displayed as an image on a displaysurface. Application of this technology to a small mobile device enablesa display and a button arrangement to be shared, and provides greatadvantages of increasing the size of the screen or saving the space ofan operating section and reducing the number of parts.

Thus, the “touch panel” generally refers to a panel-shaped contactdetecting device combined with a display device.

However, providing a touch panel on a liquid crystal panel increases thethickness of the whole of the liquid crystal module. Accordingly, aliquid crystal display element provided with a capacitance type touchpanel which element has a structure suitable for reduction in thicknesshas been proposed in Japanese Patent Laid-Open No. 2008-9750 (referredto as Patent Document 1 hereinafter), for example.

A capacitance type touch sensor has driving electrodes and a pluralityof detecting electrodes forming a capacitance with each of the pluralityof driving electrodes. The driving electrodes may be separated or notseparated. When the driving electrodes are separated, the drivingelectrodes may be disposed in a separation direction orthogonal to thedetecting electrodes. In this case, one of the driving electrodes andthe detecting electrodes may be referred to as “X-(direction)electrodes,” and the other of the driving electrodes and the detectingelectrodes may be referred to as “Y-(direction) electrodes.”

Japanese Patent Laid-Open No. 2008-129708 (referred to as PatentDocument 2 hereinafter), for example, proposes a touch panel structurehaving non-conducting transparent electrodes between patterns so as toprevent transparent electrodes from being visually perceived whendetecting electrodes are patterned.

When a device for non-visualization is provided by a touch panel aloneas in Patent Document 2, the patterns of the transparent electrodescannot be visually perceived to some degree. On the other hand, evenwhen there is some difference in transmittance in each pixel on a liquidcrystal side, the difference is a level that presents no problem, andthus a sufficient measure for non-visualization is taken.

SUMMARY OF THE INVENTION

However, when a touch panel in which a measure for non-visualization istaken is externally laminated to a liquid crystal display panel in whicha measure for non-visualization is similarly taken, a transparentelectrode pattern may become more noticeable than before the lamination.

This phenomenon is considered to be caused by interference between asubtle difference in transmittance between pixels and a repetitivepattern of transparent electrodes in a touch panel (contact detectingdevice) such that the interference is in cycles visible to the human eyesuch as interference fringes or the like when the touch panel (contactdetecting device) is superimposed on a display device such as a liquidcrystal display panel or the like.

A substrate where transparent electrodes are disposed to cancel thepattern of the transparent electrodes in the large cycles is needed,thus increasing the thickness of the display device and leading to anincrease in the number of steps.

The present invention provides a display device that can achieve thenon-visualization of a transparent electrode pattern even in aconstitution where detecting electrodes and the like for providing afunction of a touch sensor are formed integrally within a display panel.

The present invention provides a method of manufacturing a displaydevice which method does not increase cost for the achievement.

A display device related to a first embodiment of the present inventionhas a substrate, a plurality of pixel electrodes, a display functionallayer, a driving electrode, and a plurality of detecting electrodes.

The plurality of pixel electrodes are arranged in a form of a matrix ina plane parallel with the substrate.

The display functional layer exerts an image display function on a basisof an image signal supplied to the pixel electrodes.

The driving electrode is opposed to the plurality of pixel electrodes.

The plurality of detecting electrodes are arranged in a form of a planeopposed to the driving electrode, are separated and arranged at a pitchof a natural number multiple of an arrangement pitch of the pixelelectrodes in one direction in the arrangement plane, and are eachcapacitively coupled with the driving electrode.

In the display device, desirably, floating electrodes are arrangedbetween the detecting electrodes in an arrangement of the detectingelectrodes, and an arrangement pitch of the detecting electrodes, anarrangement pitch of the floating electrodes, and an arrangement pitchof the detecting electrodes and the floating electrodes are a naturalnumber multiple of the arrangement pitch of the pixel electrodes.

The arrangement pitch of the pixel electrodes is a pixel pitch. Themagnitude of the pixel pitch is predetermined by dimensions of thedisplay device, resolution of image display, a limitation imposed bymicromachining techniques, and the like. On the other hand, the pitch ofthe plurality of detecting electrodes is determined from a viewpoint ofobject detection, which does not have a close relation to a displayside. That is, the pitch of the plurality of detecting electrodes isdetermined from resolution of detection of size of an object to bedetected, a necessary detection signal level, and the like. In general,when the arrangement pitch of detecting electrodes is too small such asthe pixel pitch, parasitic capacitance between detecting lines isincreased, and a change in capacitance when a finger, a conductiveobject or the like approaches is decreased. When the arrangement pitchof the detecting electrodes is too large, resolution of object detectionfalls.

In the above-described constitution, when an object such as a finger ofa person, a conductive pen or the like comes into proximity to theplurality of detecting electrodes, the capacitance of a detectingelectrode at that position is changed due to coupling of an externalcapacitance. The coupling of the external capacitance changes an inducedvoltage of the detecting electrode forming the capacitance. A detectingcircuit connected to an end of the detecting electrode determineswhether an object is present on the basis of the change.

In the present invention, first, floating electrodes are formed betweenpixel electrodes to adjust an electrode pitch to a pixel pitch in thewhole of a layer of arrangement of detecting electrodes. At this time,the adjustment to the pixel pitch is attained in all intervals betweenthe pixel electrodes, between the floating electrodes, and between thepixel electrodes and the floating electrodes. Specifically, theadjustment to the pixel pitch is achieved by making the pitches of theelectrodes to be adjusted a natural number multiple of the pixel pitch.

Thus, in the display device as a whole, subtle difference intransmittance between pixels is not converted into difference intransmittance in large cycles such as interference fringes or the like.

In this case, because the adjustment to the pixel pitch is attained inall intervals between the pixel electrodes, between the floatingelectrodes, and between the pixel electrodes and the floatingelectrodes, transmittance in the display device as a whole isuniformized. When the transmittance is thus uniformized, variations inthe pixel pitch to a certain degree do not affect non-visualization ofthe electrodes. When such variations are fluctuations less than thepixel pitch, for example, the variations do not affect thenon-visualization.

A method of manufacturing a display device according to a secondembodiment of the present invention includes the steps of: forming aplurality of pixel electrodes on a first substrate; forming a drivingelectrode on one of the first substrate and a second substrate; forminga plurality of detecting electrodes on one of the second substrate andanother substrate; and filling a liquid crystal between the firstsubstrate and the second substrate. The step of forming the plurality ofdetecting electrodes further includes a step of forming a transparentelectrode layer and a step of dividing the transparent electrode layer.In the step of dividing the transparent electrode layer, the pluralityof detecting electrodes arranged in a form of a plane opposed to thedriving electrode and having a pattern separated in one direction in theplane of arrangement and a plurality of floating electrodes arrangedbetween the detecting electrodes in an arrangement of the detectingelectrodes are formed simultaneously. At this time, the transparentelectrode layer is patterned such that the arrangement pitch of thedetecting electrodes, the arrangement pitch of the floating electrodes,and the arrangement pitch of the detecting electrodes and the floatingelectrodes are a natural number multiple of the arrangement pitch of thepixel electrodes in the one direction.

According to the manufacturing method as described above, there is noincrease in processes for the arrangement and formation of the floatingelectrodes.

According to the present embodiments, a display device achievingnon-visualization of a transparent electrode pattern by the displaydevice as a whole can be provided.

According to the present embodiments, a method of manufacturing adisplay device which method does not increase cost for non-visualizationof a transparent electrode pattern by the display device as a whole canbe provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are an equivalent circuit diagram and a schematicsectional view of assistance in explaining operation of touch sensorsections according to a first to a fourth embodiment;

FIGS. 2A and 2B are a similar equivalent circuit diagram and a similarschematic sectional view when a finger is in contact with or inproximity to the touch sensor section shown in FIGS. 1A and 1B;

FIGS. 3A, 3B, and 3C are diagrams showing an input-output waveform of atouch sensor section according to an embodiment;

FIGS. 4A, 4B, 4C, and 4D are plan views and a schematic sectional viewof an electrode pattern for touch detection of display devices accordingto the first to fourth embodiments and connection to a driving circuitfor the electrode pattern;

FIG. 5 is an equivalent circuit diagram of a pixel circuit of thedisplay devices according to the first to fourth embodiments;

FIG. 6 is an enlarged plan view of a liquid crystal display sectionafter formation of pixel electrodes according to the first embodiment;

FIGS. 7A and 7B are enlarged plan views of the liquid crystal displaysection after formation of counter electrodes according to the firstembodiment;

FIGS. 8A and 8B are enlarged plan views of the liquid crystal displaysection after formation of detecting (driving) electrodes according tothe first embodiment;

FIGS. 9A and 9B are enlarged plan views when a liquid crystal displaysection according to the second embodiment has floating electrodes;

FIGS. 10A and 10B are enlarged plan views of floating electrodes anddetecting electrodes in a different arrangement from FIGS. 9A and 9B;

FIG. 11 is a plan view corresponding to FIGS. 9A and 9B with relation toa color arrangement added;

FIG. 12 is a plan view corresponding to FIGS. 10A and 10B with relationto the color arrangement added;

FIG. 13 is a plan view of detecting electrodes provided with verticalslits according to the third embodiment;

FIGS. 14A and 14B are plan views of detecting electrodes provided withhorizontal (or dot-shaped) slits according to the third embodiment;

FIG. 15 is a schematic sectional structure diagram showing an example ofconstitution of an example of modification;

FIG. 16 is a schematic sectional structure diagram showing anotherexample of constitution of the example of modification; and

FIG. 17 is a schematic sectional structure diagram showing anotherexample of constitution of the example of modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described withreference to the drawings by taking as an example a case where a displaydevice is a liquid crystal display device.

Description will hereinafter be made in the following order.

-   1. First Embodiment: Both Driving Electrode and Detecting Electrode    Adjusted to Pixel Pitch-   2. Second Embodiment: Improving Similarity to Detecting Electrode by    Arrangement and Shape of Floating Electrode-   3. Third Embodiment: Improving Similarity to Floating Electrode by    Slit of Detecting Electrode-   4. Example of Modification: Modification Relating Particularly to    Sectional Structure

In the following embodiments, a liquid crystal display device providedwith a so-called touch sensor which device is formed by integrating thefunction of the touch sensor into a display panel will be taken as anexample.

1. First Embodiment

An electrode that is provided farther into a panel than the detectingelectrode (electrode to which a finger or the like is brought intoproximity on the side of a display surface) of a touch sensor and whichis another electrode for forming a capacitance between the electrode andthe detecting electrode will be referred to as a driving electrode.While the driving electrode may be exclusively used for the touchsensor, the driving electrode in this case is an electrode serving adouble purpose to perform scanning driving of the touch sensor andso-called VCOM driving of an image display device simultaneously, as aconstitution desirable for reduction in thickness.

With this case as an example, the present embodiment will be describedbelow with reference to drawings. Incidentally, simply referring to thedriving electrode as a driving electrode is confusing as to whichdriving is indicated, and therefore the driving electrode will bereferred to as a counter electrode in the following.

While sensor detection accuracy is proportional to the number of drivingelectrodes and detecting electrodes, providing sensor output linesseparately from the detecting electrodes increases the number of piecesof wiring enormously. Thus, to make the detecting electrodes functionalso as sensor output lines, a driving method is desirable whichsubjects one of a plurality of driving electrodes to alternating-currentdriving and shifts the object of operation of the alternating-currentdriving within the arrangement of the plurality of driving electrodesarranged at a certain pitch and at predetermined intervals. A directionof shifting the object of operation as the driving electrode willhereinafter be referred to as a scanning direction. The scanningdirection corresponds to “another direction” in the present invention,and a direction of separation and arrangement of a plurality ofdetecting electrodes corresponds to “one direction” in the presentinvention.

In a method of scanning the object of this alternating-current drivingin the scanning direction (another direction), when changes in potentialof the detecting electrodes are observed in such a manner as to followthe scanning, contact with or proximity to the surface of the touchpanel by an object to be detected can be detected from a position at thetime of scanning when a potential change occurred.

The application of the present invention is not limited to a drivingmethod that divides driving electrodes in another direction, drives apredetermined number of driving electrodes at a time, and shifts thedriving object. However, the driving method is desirable for reductionin thickness. Therefore, in the following embodiment, description willbe made mainly supposing the driving method.

[Basic Constitution and Operation of Touch Detection]

First, the basics of touch detection in the display device according tothe present embodiment will be described as an item common to fourembodiments with reference to FIGS. 1A to 3C.

FIG. 1A and FIG. 2A are equivalent circuit diagrams of a touch sensorsection. FIG. 1B and FIG. 2B are diagrams of structure (schematicsectional views) of the touch sensor section. FIGS. 1A and 1B representa case where a finger as an object to be detected is not in proximity toa sensor. FIGS. 2A and 2B represent a case where the finger is inproximity to or in contact with the sensor.

The illustrated touch sensor section is a capacitance type touch sensor,and is composed of a capacitive element, as shown in FIG. 1B and FIG.2B. Specifically, the capacitive element (capacitance) C1 is formed of adielectric D and a pair of electrodes arranged so as to be opposed toeach other with the dielectric D interposed between the electrodes, thatis, a driving electrode E1 and a detecting electrode E2.

As shown in FIG. 1A and FIG. 2A, the driving electrode E1 of thecapacitive element C1 is connected to an alternating-current signalsource S that generates an AC pulse signal Sg. The detecting electrodeE2 of the capacitive element C1 is connected to a voltage detector DET.At this time, the detecting electrode E2 is grounded via a resistance R,whereby a DC level is electrically fixed.

The AC pulse signal Sg of a predetermined frequency, for example a few[kHz] to a few ten [kHz] is applied from the alternating-current signalsource S to the driving electrode E1. The waveform of the AC pulsesignal Sg is illustrated in FIG. 3B.

Then, an output waveform (detection signal Vdet) shown in FIG. 3Aappears in the detecting electrode E2.

Incidentally, as will be described later in detail, in embodiments ofthe present invention, the driving electrode E1 corresponds to a counterelectrode for liquid crystal driving (electrode opposed to pixelelectrodes and common to a plurality of pixels). In this case, forliquid crystal driving, the counter electrode is subjected toalternating-current driving referred to as so-called Vcom inversiondriving. Thus, in embodiments of the present invention, a common drivingsignal Vcom for the Vcom inversion driving is used also as the AC pulsesignal Sg for driving the driving electrode E1 for the touch sensor.

In a state shown in FIGS. 1A and 1B in which a finger is not in contact,the driving electrode E1 of the capacitive element C1 is subjected toalternating-current driving, and an alternating-current detection signalVdet appears in the detecting electrode E2 as the driving electrode E1is charged and discharged. The detection signal at this time willhereinafter be written as an “initial detection signal Vdet0.” Thedetecting electrode E2 side is DC-grounded, but is not grounded in termsof high frequency. Therefore, there is no discharge path of alternatingcurrent, and the pulse peak value of the initial detection signal Vdet0is relatively high. However, when a time passes after the rising of theAC pulse signal Sg, the pulse peak value of the initial detection signalVdet0 gradually decreases due to a loss. FIG. 3C shows a waveform in anenlarged state together with a scale. The pulse peak value of theinitial detection signal Vdet0 decreases by about 0.5 [V] from aninitial value of 2.8 [V] with the passage of a short time due to ahigh-frequency loss.

When the finger comes into contact with the detecting electrode E2 orapproaches the detecting electrode E2 to a close range so as to producean effect from the initial state, as shown in FIG. 2A, a circuit statechanges to a state equivalent to that of a capacitive element C2 beingconnected to the detecting electrode E2. This is because a human body isequivalent to a capacitance having one side grounded in terms of highfrequency.

In this contact state, a discharge path of an alternating-current signalvia the capacitive elements C1 and C2 is formed. Thus, as the capacitiveelements C1 and C2 are charged and discharged, alternating currents I1and I2 flow through the capacitive elements C1 and C2, respectively.Therefore the initial detection signal Vdet0 is voltage-divided into avalue determined by a ratio between the capacitive elements C1 and C2 orthe like, and the pulse peak value decreases.

A detection signal Vdet1 shown in FIG. 3A and FIG. 3C appears in thedetecting electrode E2 when the finger comes into contact. FIG. 3C showsthat an amount of decrease of the detection signal is about 0.5 [V] to0.8 [V].

The voltage detector DET shown in FIGS. 1A and 1B and FIGS. 2A and 2Bdetects the contact of the finger by detecting the decrease in thedetection signal using a threshold value Vth, for example.

[Constitution of Display Device]

FIGS. 4A to 4C are plan views specialized in an arrangement ofelectrodes of the display device according to the present embodiment andcircuits for driving the electrodes and for detection. FIG. 4Dschematically shows a sectional structure of the display deviceaccording to the present embodiment. FIG. 4D shows a section of sixpixels in a row direction (pixel display line direction), for example.FIG. 5 is a diagram of an equivalent circuit of a pixel.

The display device illustrated in FIGS. 4A to 4D is a liquid crystaldisplay device having a liquid crystal layer as a “display functionallayer.”

As described above, the liquid crystal display device has an electrode(counter electrode) of two electrodes opposed to each other with theliquid crystal layer interposed between the electrodes, which electrodeis common to a plurality of pixels and supplied with a common drivingsignal Vcom giving a reference voltage for a signal voltage forgradation display in each pixel. In embodiments of the presentinvention, this counter electrode is used also as an electrode forsensor driving.

In FIG. 4D, for easy viewing of the sectional structure, the counterelectrode, a pixel electrode, and a detecting electrode, which form amain constitution of the present invention, are hatched, whereashatching of other parts (substrates, insulating films, functional filmsand the like) is omitted. The omission of the hatching is similarly madein other subsequent diagrams of sectional structure.

The liquid crystal display device 1 has pixels PIX as shown in FIG. 5which pixels are arranged in the form of a matrix.

As shown in FIG. 5, each pixel PIX has a thin film transistor (TFT)(hereinafter written as a TFT 23) as a selecting element of the pixel,an equivalent capacitance C6 of a liquid crystal layer 6, and a storagecapacitor (referred to also as an additional capacitance) Cx. Anelectrode on one side of the equivalent capacitance C6 representing theliquid crystal layer 6 is a pixel electrode 22 separated for each pixeland arranged in the form of a matrix. An electrode on the other side ofthe equivalent capacitance C6 is a counter electrode 43 common to aplurality of pixels.

The pixel electrode 22 is connected to one of the source and the drainof the TFT 23. A signal line SIG is connected to the other of the sourceand the drain of the TFT 23. The signal line SIG is connected to avertical driving circuit not shown in the figure. A video signal havinga signal voltage is supplied from the vertical driving circuit to thesignal line SIG.

The counter electrode 43 is supplied with a common driving signal Vcom.The common driving signal Vcom is generated by inverting a positive ornegative potential with a central potential as a reference in eachhorizontal period (1 H).

The gate of the TFT 23 is electrically made common to all pixels PIXarranged in a row direction, that is, a horizontal direction of adisplay screen. Thereby a scanning line SCN is formed. The scanning lineSCN is supplied with a gate pulse for opening and closing the gate ofthe TFT 23, which gate pulse is output from the vertical driving circuitnot shown in the figure. Therefore the scanning line SCN is referred toalso as a gate line.

As shown in FIG. 5, the storage capacitor Cx is connected in parallelwith the equivalent capacitance C6. The storage capacitor Cx is providedto prevent a shortage of accumulating capacitance by the equivalentcapacitance C6 and a decrease in writing potential due to a leakagecurrent of the TFT 23 or the like. The addition of the storage capacitorCx also contributes to the prevention of flicker and improvement inuniformity of screen luminance.

As viewed in a sectional structure (FIG. 4D), the liquid crystal displaydevice 1 having such pixels arranged therein includes: a substrate(hereinafter referred to as a driving substrate 2) in which the TFT 23shown in FIG. 5 is formed at a position not appearing in the section andwhich substrate is supplied with a driving signal (signal voltage) forthe pixels; a counter substrate 4 disposed so as to be opposed to thedriving substrate 2; and the liquid crystal layer 6 disposed between thedriving substrate 2 and the counter substrate 4.

The driving substrate 2 has a TFT substrate 21 (a substrate body sectionis formed by glass or the like) as a circuit substrate in which the TFT23 in FIG. 5 is formed and a plurality of pixel electrodes 22 arrangedin the form of a matrix on the TFT substrate 21.

A display driver (the vertical driving circuit, a horizontal drivingcircuit and the like) not shown in the figure for driving each pixelelectrode 22 is formed in the TFT substrate 21. In addition, the TFT 23shown in FIG. 5 as well as wiring such as the signal line SIG, thescanning line SCN and the like is formed in the TFT substrate 21. Adetecting circuit for performing touch detecting operation to bedescribed later may be formed in the TFT substrate 21.

The counter substrate 4 has a glass substrate 41, a color filter 42formed on one surface of the glass substrate 41, and the counterelectrode 43 formed on the color filter 42 (liquid crystal layer 6side). The color filter 42 is formed by periodically arranging colorfilter layers of three colors of red (R), green (G), and blue (B), forexample, with each pixel PIX (pixel electrode 22) associated with one ofthe three colors R, G, and B. Incidentally, there are cases where apixel associated with one color is referred to as a sub-pixel andsub-pixels of the three colors R, G, and B is referred to as a pixel. Inthis case, however, sub-pixels are also written as pixels PIX.

The counter electrode 43 serves also as a sensor driving electrodeforming a part of a touch sensor performing touch detecting operation,and corresponds to the driving electrode E1 in FIGS. 1A and 1B and FIGS.2A and 2B.

The counter electrode 43 is connected to the TFT substrate 21 by acontact conductive column 7. The common driving signal Vcom of analternating-current pulse waveform is applied from the TFT substrate 21to the counter electrode 43 via the contact conductive column 7. Thiscommon driving signal Vcom corresponds to the AC pulse signal Sgsupplied from the driving signal source S in FIGS. 1A and 1B and FIGS.2A and 2B.

A detecting electrode 44 is formed on the other surface (display surfaceside) of the glass substrate 41. Further, a protective layer 45 isformed on the detecting electrode 44. The detecting electrode 44 forms apart of the touch sensor, and corresponds to the detecting electrode E2in FIGS. 1A and 1B and FIGS. 2A and 2B. A detecting circuit forperforming touch detecting operation to be described later may be formedin the glass substrate 41.

The liquid crystal layer 6 modulates light passing through the liquidcrystal layer 6 in a direction of thickness (direction in which theelectrodes are opposed to each other) according to a state of anelectric field applied to the liquid crystal layer 6 as a “displayfunctional layer.” As the liquid crystal layer 6, liquid crystalmaterials in various modes such as TN (Twisted Nematic), VA (VerticalAlignment), and ECB (Electrically Controlled Birefringence), forexample, are used.

Incidentally, alignment films are respectively disposed between theliquid crystal layer 6 and the driving substrate 2 and between theliquid crystal layer 6 and the counter substrate 4. In addition,polarizers are respectively disposed on the non-display surface side(that is, the back side) of the driving substrate 2 and on the displaysurface side of the counter substrate 4. These optical functional layersare not shown in FIGS. 4A to 4D.

As shown in FIG. 4A, the counter electrode 43 is divided in a directionof rows or columns of the pixel arrangement, or a column direction(vertical direction of the figure) in the present example. The directionof this division corresponds to a direction of scanning of pixel linesin display driving, that is, a direction in which the vertical drivingcircuit not shown in the figure sequentially activates scanning linesSCN.

The counter electrode 43 is divided into n pieces in total. Thus,counter electrodes 43_1, 43_2, . . . , 43_m, . . . , 43_n are arrangedin the form of a plane having a stripe-shaped pattern that is long in arow direction, and are spread all over in parallel with each other witha clearance from each other within the plane.

The divided arrangement pitch of the n divided counter electrodes 43_1to 43_n is set at a natural number multiple of a pixel (sub-pixel) pitchor the arrangement pitch of the pixel electrodes.

Incidentally, a reference “EU” shown in FIGS. 4A and 4C has a set of m(>2) counter electrodes, and alternating-current driving is performed inthis unit. This unit will be referred to as an alternating-currentdriven electrode unit EU. The alternating-current driving unit is largerthan one pixel line for purposes of increasing the capacitance of thetouch sensor and increasing the detecting sensitivity of the touchsensor. On the other hand, the alternating-current driven electrode unitEU is shifted by a natural number multiple of the pixel pitch unit,whereby the shift can be made invisible.

On the other hand, in the Vcom driving thus having thealternating-current driven electrode unit EU of counter electrodes as aunit, the shift operation of the Vcom driving is performed by a Vcomdriving circuit 9 as an “alternating-current driving scanning section”provided within the vertical driving circuit (writing driving scanningsection) not shown in the figure. The operation of the Vcom drivingcircuit 9 can be considered equal to an “operation of moving analternating-current signal source S (see FIGS. 1A and 1B and FIGS. 2Aand 2B) for performing simultaneous Vcom alternating-current driving ofwiring of m counter electrodes in the column direction and scanning theselected counter electrodes in the column direction while changing theselected counter electrodes one by one.”

The Vcom driving of electrode driving and non-visualization of thedriving electrode by the Vcom driving are desirable, but are notessential in the present invention.

The present invention provides a constitution for non-visualization of apattern due to the arrangement of transparent electrodes in the displaydevice as a whole irrespective of whether shift driving is performed ornot.

[Divided Arrangement Pitch of Counter Electrodes (Driving Electrodes)]

The divided arrangement pitch of detecting electrodes will first bedescribed in more detail.

FIG. 6 is an enlarged plan view of a display section in a process ofbeing manufactured in which display section pixel electrodes 22 areformed.

In the plan view in a state where the pixel electrodes 22 illustrated inFIG. 6 are formed, a plurality of gate lines (scanning lines SCN: seeFIG. 5) arranged in the form of parallel stripes in a row direction(x-direction) intersect a plurality of signal lines SIG arranged in theform of parallel stripes in a column direction (y-direction). Arectangular region enclosed by two arbitrary scanning lines SCN and twoarbitrary signal lines SIG defines a pixel (sub-pixel) PIX. A pixelelectrode 22 is formed in a rectangular isolated pattern slightlysmaller than each pixel PIX. Thus, a plurality of pixel electrodes 22are arranged in a plane in the form of a matrix.

FIGS. 7A and 7B are enlarged plan views after counter electrodes(driving electrodes) 43 are formed above in the z-direction of FIG. 6.

As shown in FIGS. 7A and 7B, the counter electrodes 43 are formed aswiring that is long in the x-direction parallel with the scanning linesSCN.

In FIG. 7A, a counter electrode 43 is formed with a width of a two-pixelpitch. In FIG. 7B, counter electrodes 43 are formed with a width of aone-pixel pitch. The counter electrodes 43 may be separated and arrangedat a pitch that is a natural number multiple of a pixel pitch, that is,three times the pixel pitch or more in the y-direction.

From the above, one of features of the present embodiment is that aplurality of counter electrodes 43 as “driving electrodes” are separatedand arranged at a pitch that is a natural number multiple of the pixelpitch in another direction (y-direction in this case).

While an original counter electrode is common to all pixels, it sufficesfor the Vcom driving circuit 9 shown in FIGS. 4A to 4D to drive a partof counter electrodes which part is necessary for display. This providesan advantage of being able to decrease the driving power of eachalternating-current signal source S forming the Vcom driving circuit 9and miniaturize the driving circuit of the Vcom driving circuit 9 as awhole.

FIGS. 8A and 8B are enlarged plan views of the display section in theprocess of being manufactured in which display section detectingelectrodes 44 are further arranged above in the z-direction of FIGS. 7Aand 7B. Incidentally, in FIGS. 8A and 8B, for easy viewing of relationto pixels, the counter electrodes 43 arranged in FIGS. 7A and 7B areomitted intentionally.

The detecting electrodes 44 enable position detection with a higherresolution when wiring is performed for a shorter distance between thedetecting electrodes 44. However, too short a distance is not desirablebecause a capacitance between an input device and a detecting electrodeis reduced.

Though depending on the size of the input device and the size of thedisplay pixels, the width in the x-direction of the detecting electrodes44 is desirably about 10 to 2000 [μm] when a touch sensor is assumed asan input device. In the case of an object with a thin tip such as aconductive pen or the like, the width of the detecting electrodes 44 isdesirably about 5 to 500 [μm].

The detecting electrodes 44 are arranged in synchronism with pixel sizein a range of the above-described desirable width. Specifically, in theexample of FIG. 8A, the arrangement pitch in the x-direction of thedetecting electrodes 44 is set at three times the pixel pitch. In theexample of FIG. 8B, the width in the x-direction of the detectingelectrodes 44 is about three times the pixel pitch. The arrangementpitch of the detecting electrodes 44 in the x-direction in FIG. 8B canbe a natural number multiple of the pixel pitch, that is, four times thepixel pitch or more.

The above being description of the synchronism between the arrangementpitch of the detecting electrodes 44 and the pixel pitch, thearrangement of the detecting electrodes 44 is more desirablysynchronized with a color cycle.

For example, consideration will be given to a case where color regionsof the color filter 42 of RGB are repeated in the x-direction in theexamples of FIGS. 8A and 8B.

In this case, in the example of FIG. 8A, the arrangement pitch in thex-direction of the detecting electrodes 44 is set at a multiple of threetimes the pixel pitch, that is, a three-pixel pitch, a six-pixel pitch,. . . . In the example of FIG. 8B, the width in the x-direction of thedetecting electrodes 44 is set at about a multiple of three times thepixel pitch, and the width of separation between the detectingelectrodes 44 is also set at about a multiple of three times the pixelpitch.

Thus, in FIG. 8A, the detecting electrodes 44 are arranged so as tocorrespond to a specific color, for example green (G). In FIG. 8B, thedetecting electrodes 44 cover a region of three colors of RGB.

By thus synchronizing with the pixel pitch and uniformizing colorarrangement with respect to the detecting electrodes 44, manifestationof slight difference in transmittance due to color difference isprevented more.

As a result, the pixel electrodes 22, the counter electrodes 43, and thedetecting electrodes 44 made of transparent electrode materials allcorrespond to the pixel pitch. In addition, a manner of superimpositionbetween the counter electrodes 43 and the detecting electrodes 44 doesnot differ between pixels of a specific color.

Incidentally, the pixel electrodes 22, the counter electrodes 43, andthe detecting electrodes 44 are preferably formed of transparentelectrode materials. These electrodes may be formed of ITO and IZO aswell as organic conductive films as transparent electrode materials.

2. Second Embodiment

When there is no layer of a transparent electrode material betweendetecting electrodes 44 as in the first embodiment, difference intransmittance can occur between colors. In the present embodiment,floating electrodes are arranged to match transmittance between thedetecting electrodes 44 to the transmittance of the detecting electrodes44 themselves.

FIGS. 9A and 9B and FIGS. 10A and 10B are enlarged plan views showingfloating electrodes arranged between detecting electrodes 44.

As shown in FIGS. 9A and 9B and FIGS. 10A and 10B, floating electrodes46A are arranged between detecting electrodes 44 to reduce difference intransmittance between colors.

The floating electrodes 46A in the present embodiment may have a lineshape similar to that of detecting electrodes 44, as shown in FIG. 9A.Alternatively, as shown in FIG. 9B, floating electrodes 46 may bearranged in the form of rectangular tiles divided in substantially thesize of a pixel.

Thus, it suffices for the floating electrodes 46 to have an arrangementpitch corresponding to a natural number multiple of a pixel pitch in atleast one of an x-direction (one direction) and a y-direction (anotherdirection).

Considering pattern similarity to the detecting electrodes 44, it isdesirable that the floating electrodes 46 have the same line shape inthe y-direction as the detecting electrodes 44 (FIG. 9A).

On the other hand, because a large size of one floating electrode 46causes a high stray capacitance, a voltage change in a counter electrode(driving electrode) 43 in a space between detecting electrodes 44 maynot be transmitted easily as a capacitance change on an externalcapacitance side on the side of an object to be detected. As a result,the level of a detection signal may be decreased.

The pattern similarity between the detecting electrodes 44 and thefloating electrodes 46 for this non-visualization and the magnitude ofan optimum stray capacitance for increasing detecting sensitivity areconsidered to be in tradeoff relation.

Accordingly, as shown in other embodiments below, in the presentinvention, various forms of stray capacitance are tolerated to strike abalance between non-visualization and an increase in sensitivity fromthe viewpoint of the above-described tradeoff as long as the requirementof a natural number multiple of the pixel pitch in the x-direction andthe y-direction is satisfied.

The patterns of FIGS. 8A and 8B described above (first embodiment) arevisually perceived unless the cycle is 100 [μm] or less.

On the other hand, when floating electrodes 46 having substantially anatural number multiple of the size of a pixel electrode 22 areprovided, the detecting electrodes and the floating electrodes 46 maynot be distinguished from each other, and the pattern is not easilyperceived even when the cycle is more than 100 [μm].

At this time, it is desirable to shorten distance between the detectingelectrodes and the floating electrodes 46 as much as possible. Thoughdepending on the size of display pixels, an aperture ratio and the like,this distance is desirably about 1 to 30 [μm], and is more desirably 1to 15 [μm]. Further, as another index, it is desirable to cover 85% ormore of an effective area with the detecting electrodes and the floatingelectrodes 46.

FIGS. 10A and 10B are different from FIGS. 9A and 9B in that thearrangement of the detecting electrodes 44 and the floating electrodes46 is shifted by ½ of a pixel in the x-direction with respect to thearrangement of pixel electrodes 22. This does not cause a change in thearrangement pitch corresponding to a natural number multiple of thepixel pitch, and does not change the regularity of electrodearrangement. When signal lines SIG having low light transmittance arearranged in a region easily transmitting light between the detectingelectrodes 44 and the floating electrodes 46, the efficiency of use oflight is decreased. In addition, a difference between the transmittanceof the part of the signal lines SIG and the transmittance of other partsis increased. Accordingly, it may be desirable to employ the arrangementshifted by ½ of a pixel from viewpoints of both improvements in theefficiency of use of light and the uniformity of transmittance.

In this case, the detecting electrodes 44 and the floating electrodes 46are formed of a same transparent electrode material in a same step, thatis, photolithography technology. The number of steps is not increased ascompared with the cases of FIGS. 8A and 8B where the floating electrodes46 are not present.

According to the first and second embodiments described above, both thecounter electrodes 43 and the detecting electrodes 44 as transparentelectrodes other than the pixel electrodes 22 have an arrangement pitchthat is a natural number multiple of the pixel pitch in other than theline direction of a long dimension as signal lines, that is, in a widthdirection.

In addition, the electrode pitch in the width direction of the counterelectrodes 43 and the detecting electrodes 44 is desirably defined suchthat both the counter electrodes 43 and the detecting electrodes 44 aresuperimposed in the same manner in a specific color.

In particular, in the second embodiment, the relation between thecounter electrodes 43 and the detecting electrodes 44 is the same foreach color, and the relation between the counter electrodes 43 and thefloating electrodes 46 is the same for some colors. In addition, thefloating electrodes 46 have such a shape and an arrangement as toresemble the detecting electrodes 44 as much as possiblemacroscopically.

According to the first and second embodiments, the relation between thecounter electrodes (driving electrodes) 43 and the detecting electrodes44 is thus a natural number multiple of the pixel pitch, and thereforethe relation does not vary periodically. In addition, periodic variationis suppressed as much as possible in each color and between colors.

As a result, a subtle difference in transmittance between pixels(between colors in particular) is not easily perceived by the human eye.A minimum value of such a divided arrangement pitch is desirably suchthat the cycle in particular is 100 [μm] or less.

In either of the first and second embodiments, it is desirable that aseparation region between electrodes be set on a same color of the colorfilter. For this, at least the arrangement pitch in the x-direction ofthe detecting electrodes 44 is defined as a natural number multiple ofthree times the pixel pitch. This requirement is satisfied in any of thecases of FIGS. 8A to 10B.

Thereby, a difference in decrease in transmittance in a same color canbe eliminated.

As examples for making this clearer, FIG. 11 and FIG. 12 represent caseswhere detecting electrodes 44 have a width in the x-direction of athree-pixel pitch and have an arrangement pitch of a 12-pixel pitch.

In FIG. 11, signal lines SIG are arranged in inter-electrode separationregions between floating electrodes 46 and inter-electrode separationregions between floating electrodes 46 and detecting electrodes 44. FIG.11 is similar to FIGS. 9A and 9B in this respect.

On the other hand, in FIG. 12, as in FIGS. 10A and 10B, inter-electrodeseparation regions between floating electrodes 46 or between floatingelectrodes 46 and detecting electrodes 44 are arranged so as to passthrough about the center in the x-direction of pixel electrodes 22 of apredetermined color, for example (B).

This provides a high efficiency of use of light, and makes periodicstripes less visible. For example, when disposition of aninter-electrode separation region on a specific color region andnon-disposition of an inter-electrode separation region on regions ofsome same colors are repeated, a large difference in transmittanceoccurs in cycles in which inter-electrode separation regions arearranged. Because the human eye is sensitive to a difference intransmittance at 100 [μm] or more, periodic stripes long in they-direction are visually perceived due to the extension of such a cycle.In order to prevent the occurrence of stripes, inter-electrodeseparation regions have to be arranged on all specific colors.Alternatively, a loss in transmittance can be reduced by superimposingthe part of the occurrence of stripes on other wiring.

3. Third Embodiment

The first and second embodiments bring the transmittance of regionsbetween detecting electrodes close to the transmittance of the detectingelectrodes 44 by the arrangement of floating electrodes 46.

However, a case is assumed in which there is a limitation preventingenlargement of each of the floating electrodes 46 in order to maintaindetecting sensitivity, as described above.

In such a case, it is possible to make the pattern of detectingelectrodes 44 resemble the arrangement pattern of floating electrodes46.

FIG. 13 and FIGS. 14A and 14B show an example of the pattern ofdetecting electrodes 44 determined for that purpose. Incidentally, inFIG. 13 and FIGS. 14A and 14B, the detecting electrodes 44 and floatingelectrodes 46 are not made transparent because making the detectingelectrodes 44 transparent renders the figures less easy to view.However, the detecting electrodes 44 and the floating electrodes 46 areformed of a transparent electrode material as in other cases. Aconstitution on a lower layer side thereby hidden is the same as in FIG.12.

In FIG. 13, the detecting electrodes 44 have a width of a pitch of sixpixels, and are arranged at a pitch of 12 pixels. Short line-shapedslits 47V in a y-direction passing through the center of the detectingelectrodes 44 in an x-direction are provided. Thereby, making thedetecting electrodes 44 integral and set at a same potential andincreasing pattern similarity to the floating electrodes 46 arecompatible with each other. “Pseudo inter-electrode separation regions”are formed by aligning a plurality of slits 47 in the y-direction(another direction).

In this case, the pseudo inter-electrode separation regions includingthe slits 47V and inter-electrode separation regions not including slitsare arranged so as to be superimposed on color regions of a same color(B-regions in the present example). This constitution is not essential,but is desirable to ensure the perfection of non-visualization in asense that synchronization with color can be achieved.

This effect can be achieved by slits in the x-direction as in FIG. 14Aand FIG. 14B. In this case, detecting electrodes 44 have a width ofthree pixels in relation to color arrangement.

In FIG. 14A, x-direction slits 47H long in the x-direction (widthdirection) are formed in a detecting electrode 44.

In FIG. 14B, x-direction slits are separated into the form of dots. Slitformation by dot arrangement is also desirable in order to achieve bothof suppressing a decrease in resistance value as much as possiblebecause slits in a direction of crossing the width direction of wiringlimit a current path and making the slits as a whole resemble theseparation of floating electrodes 46.

4. Examples of Modification

In the foregoing first to third embodiments, a case is taken as anexample in which case a plurality of driving electrodes are arranged soas to be separated from each other in another direction orthogonal toone direction in which a plurality of detecting electrodes are arrangedso as to be separated from each other. Also, in this example, aplurality of driving electrodes are arranged so as to be separated fromeach other, and the arrangement pitch of the plurality of drivingelectrodes is a natural number multiple of the arrangement pitch ofpixel electrodes. Thus, in the first to fourth embodiments, driving ofthe driving electrodes of the touch sensor and the display functionallayer (common voltage of the display functional layer) for liquidcrystal display or the like is performed by the same driving electrodes.This structure and the driving method are desirable because of anadvantage of being able to reduce the thickness of the (liquid crystal)display device integrated with the touch panel.

However, even when the touch panel is integrated with the display panel,the driving electrodes of the touch sensor may be provided as anotherlayer than the driving (common) electrode for (liquid crystal) display.In this case, the driving electrodes of the touch sensor may be disposedas one electrode opposed to a plurality of pixel electrodes withoutbeing separated. However, relative positional relation between aplurality of detecting electrodes and the driving electrode isdetermined such that a capacitance is formed between each of theplurality of detecting electrodes and the driving electrode (of thetouch sensor).

A liquid crystal layer 6 modulates light passing through the liquidcrystal layer 6 according to the state of an electric field. A liquidcrystal in a transverse electric field mode such for example as an FFS(Fringe Field Switching) mode or an IPS (In-Plane Switching) mode issuitably used as the liquid crystal layer 6.

FIGS. 15 to 17 show an example of structure of a transverse electricfield mode liquid crystal display device.

In the structure of FIGS. 4A to 4D, a pixel electrode 22 and a counterelectrode 43 face each other with the liquid crystal layer 6 interposedbetween the pixel electrode 22 and the counter electrode 43, and anelectric field in a vertical direction is applied to the liquid crystallayer 6 according to a voltage applied between the two electrodes.

In the transverse electric field mode, the pixel electrode 22 and thedriving electrode (counter electrode) 43 are disposed on the side of adriving substrate 2.

In the structure of FIG. 15, the counter electrode 43 is disposed on asurface on a front side (display surface side) of a TFT substrate 21,and the counter electrode 43 and a pixel electrode 22 are in proximityto each other with an insulating layer 24 interposed between the counterelectrode 43 and the pixel electrode 22. The counter electrode 43 isdisposed in the form of a line long in the direction of display lines(x-direction). The pixel electrode 22 is separated in each pixel in thatdirection.

The TFT substrate 21 has the side of the pixel electrode 22 which sideis adjacent to the liquid crystal layer 6, and is laminated to a glasssubstrate 41. The liquid crystal layer 6 is retained in terms ofstrength by a spacer not shown in FIG. 15.

A reference numeral “49” denotes a base material on the display surfaceside such as glass, transparent film or the like. A detecting electrode44 is formed on one surface of the base material 49. The detectingelectrode 44 retained by the base material 49 is fixed to the surface onthe anti-liquid crystal side of the glass substrate 41 via an adhesivelayer 48.

A first polarizer 61 is laminated to the back surface of the TFTsubstrate 21. A second polarizer 62 having a different direction ofpolarization from that of the first polarizer 61 is laminated to thedisplay surface side of the base material 49.

A protective layer not shown in FIG. 15 is formed on the display surfaceside of the second polarizer 62.

In the structure shown in FIG. 16, a color filter 42 is formed on theliquid crystal side of the glass substrate 41 in advance. The colorfilter 42 has different color regions regularly arranged for each pixel(sub-pixel).

In the structure shown in FIG. 17, a laminated structure on a displaysurface side differs from FIG. 16.

In the structure shown in FIG. 16, a detecting electrode 44 is formed ona base material 49 in advance, and laminated as a roll-shaped member,for example. In FIG. 17, on the other hand, a detecting electrode 44 isformed on the display surface side of a glass substrate 41, and a secondpolarizer 62 is laminated onto the detecting electrode 44.

Incidentally, by properly selecting the index of refraction of anadhesive layer 48 in the structures of FIG. 15 and FIG. 16 having theadhesive layer 48, further non-visualization of an electrode pattern canbe achieved.

The present invention is applicable to liquid crystal display devices ofstructures other than those of FIGS. 15 to 17 as well as other displaydevices using a transparent electrode. In addition, liquid crystaldisplay devices may be any of a transmissive type, a reflective type,and a transreflective type. The second polarizer 62 is not limited to alinear polarizer or a circular polarizer.

As described above, according to embodiments and examples ofmodification of the present invention, a display device achievingnon-visualization of a transparent electrode pattern in the displaydevice as a whole can be provided.

In addition, when a floating electrode 46 is provided, there is noincrease in the number of steps for non-visualization because a sameelectrode material as a detecting electrode 44 is patterned in a samestep. In addition, the provision of the floating electrode 46 does notincrease the thickness of the liquid crystal display device 1. As isclear from the foregoing embodiments, the floating electrode 46 is notessential, and non-visualization can be achieved by separating a counterelectrode 43 and a detecting electrode 44 at an arrangement pitch thatis a natural number multiple of a pixel pitch. When a floating electrode46 is used, non-visualization at a higher level can be achieved withoutan increase in cost.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-040728 filedin the Japan Patent Office on Feb. 24, 2009, the entire content of whichis hereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A display device comprising a display layer, thedisplay layer including: a plurality of pixel electrodes; a scanningline extending in a first direction; a signal line extending in thesecond direction crossing the first direction; a detection electrode;and an insulating layer between the detection electrode and linesincluding the scanning line and the signal line, wherein, the detectionelectrode includes one or more inner slits overlapping the scanningline, the signal line, or both the scanning line and the signal line. 2.The display device according to claim 1, wherein: the detectionelectrode is one of a plurality of detection electrodes, the detectionelectrodes are divided by a plurality of inter slits, the scanning lineis one of a plurality of scanning lines, the signal line is one of aplurality of signal lines, and the inter slits overlap the scanninglines, the signal lines, or both the scanning lines and the signallines.
 3. The display device c according to claim 1, wherein: the one ormore inner slits overlapping the scanning line extend in the firstdirection, and the one or more inner slits overlapping the signal lineextend in the second direction.
 4. The display device according to claim2, further comprising a group of floating electrodes arranged betweenthe detection electrodes, wherein, the group of floating electrodes aredivided by the inter slits.
 5. The display device according to claim 1,further comprising a detection circuit coupled to the detectionelectrodes.
 6. The display device according to claim 1, wherein, thedetection electrodes are arranged at a pitch of a natural multiplenumber of an arrangement pitch of the pixel electrodes in a rowdirection and/or a column direction, in an arrangement plane.
 7. Thedisplay device according to claim 4, wherein: the detection electrodesare arranged at a pitch of a natural multiple number of an arrangementpitch of the pixel electrodes in a row direction and/or a columndirection in an arrangement plane, and the floating electrodes arearranged at a pitch of the arrangement pitch of the pixel electrodes inthe row direction and/or the column direction, in the arrangement plane.8. The display device according to claim 1, wherein, the one or moreinner slits of the detection electrodes are located between the pixelelectrodes.
 9. The display device according to claim 2, wherein, theinter slits are located between the pixel electrodes.
 10. The displaydevice according to claim 9, wherein, the one or more inner slits of thedetection electrodes are located between the pixel electrodes.
 11. Thedisplay device according to claim 2, wherein, the inter slits areconnected to each other.
 12. The display device according to claim 4,wherein, the inter slits are connected to each other.
 13. The displaydevice according to claim 2, wherein, the inter slits and the one ormore inner slits overlap pixels of a same color.
 14. The display deviceaccording to claim 4, wherein, the inter slits and the one or more innerslits overlap pixels of a same color.